This invention relates to compounds and a method for treating disorders of the heart. In a particular aspect, this invention relates to compounds useful for the therapeutic or prophylactic treatment of cardiac disorders in animals.
A continuing need exists for the development of treatments for such cardiac disorders as ischemic heart disease, cardiac infarction, hypertension and arrythmias. Such methods, heretofore, have included administering compounds which block beta-adrenergic nervous stimuli. Compounds possessing this activity are generally referred to as beta-blockers. Beta-blockers have provided an effective adjunct to the therapeutic regimen employed by physicians to treat cardiac patients. The compounds are useful in controlling arrythmias and angina pectoris and reduce the effects of stimulation of the beta-adrenergic nervous system, i.e. primarily the effects of catecholamines which are excreted by the adrenal glands. Outside stimuli, such as physical exertion, fear, anxiety, and the like, effect many responses in the body including constriction of peripheral blood vessels and increased contractility of the heart muscle. These responses cause hypertension and increased heart work. Excessive beta-adrenergic stimulation may also be an important factor in the conversion of latent pacemakers to active pacemakers, thereby resulting in abnormal rhythms (arrythmias).
In the patient suffering from the effects of a cardiac infarction, proper recovery requires minimization of heart work. Overwork of the heart or arrythmias may result in heart failure or very dangerous ventricular fibrillation. Total rest of the heart patient is important in decreasing cardiac output, but often rest is not sufficient to eliminate the deleterious effects of anxiety and other involuntary responses of the patient to his predicament. Through the combined treatments of rest and administration of beta-blockers, the physician can minimize heart work and, therefore, improve the patient's chances for recovery.
Beta-blockers can also be useful prophylactic agents. By decreasing the work of the heart, the amount of oxygen required to be supplied to the myocardium is decreased. Such agents are, therefore, useful in controlling angina pectoris. The agents also control hypertension and arrythmias, all of which may be precursors of heart failure or stroke.
Since the responses to beta-blockers, as other agents, may vary greatly from patient to patient, it is important that the physician have a variety of such agents available, so that he may select the best one for the patient being treated.